Elastic composite materials are known in the art. For example, the Wu U.S. Pat. Nos. 5,422,172 and 5,861,074 disclose elastic laminated sheets of a nonwoven fibrous web and an elastomeric film. Wu defines the term “elastic” as meaning stretchable under force and recoverable to its original or essentially original form upon release of that force. Wu discloses that the elastic laminate may be incrementally stretched to provide a very soft fibrous finish having the appearance of nonwoven fibers with superior bond strengths, thereby providing a composite material advantageous for use in garments and other applications where a soft finish is desirable. Wu further discloses that the elastic laminate is characterized as being impervious to the passage of fluid by virtue of the elastomeric film, while maintaining a soft feel on the fibrous web surface of the laminate, although various degrees of vapor or air permeability may be achieved by providing mechanical microvoids.
Conventional processes for providing mechanical microvoids include hot needle punching, hot roll calendaring, ultrasonic perforation, or the like. Such mechanical processes may be cumbersome and/or difficult to control during high speed manufacture of composite materials. It is also to known to provide air and water vapor permeability to polymer films by including therein one or more pore-forming fillers such as calcium carbonate, followed by stretching of the films to form micropores in areas adjacent to the filler. However, it is often difficult to provide a desired degree of permeability in elastic films using such techniques. Accordingly, there is a continued desire for breathable elastic materials which may be easily manufactured.